The present invention relates generally to apparatus for providing high pressure fluid communication between generally aligned conduits that are rotatable relative to one another using pressure activated seals. In particular, but not exclusively, the disclosure relates to devices for sealing a wash pipe assembly between a fixed and rotating conduit as used in rotary drilling operations.
In applications requiring the transmission of fluid under relatively high pressure, it is sometimes necessary to interconnect a rotating conduit with a stationary conduit and to seal the connection therebetween. One such application is in drilling operations in which a fixed-to-rotating interface is located in apparatus that is supported from the derrick, and which may take the form of a swivel, a top drive unit, or similar device. The seal between the fixed and rotating parts typically includes pressure activated, elastomeric annular seals or packing rings that must be changed when seal wear or failure occurs. Seals in common use today typically must be replaced every few hundred hours of use. This replacement involves time consuming and sometimes dangerous procedures in which the replacement components and a worker are hoisted from the drill floor up to the equipment that houses the seals that are to be replaced. While suspended at a height that may be twenty to thirty feet or more above the drill floor, the worker typically utilizes a sledgehammer to hammer open certain unions allowing removal of the washpipe assembly that contains the seals. Thereafter, new seals are inserted into the assembly, and the assembly containing the new seals is hammered into place. Some conventional seal assemblies also require the use of a pressurized fluid in order to energize the pressure-activated seals once the assembly has been installed in the swivel or top drive. This again is accomplished while the worker dangles from support lines high above the drill floor. The change out of the washpipe and seal assembly is thus complicated and time consuming, and includes the danger of the worker dropping a heavy sledgehammer onto workers or equipment below.
One common washpipe assembly houses a plurality of redundant annular seals that, during replacement, are stacked in position in the seal gland housing while the worker is suspended above the drill floor. In other conventional assemblies, as mentioned above, the seals are pre-packed in a washpipe assembly before the assembly is hoisted to the swivel above the drill floor. However, in order for the assembly to be coupled into the conduits, the seals must be manipulated in order to energize the seals and cause them to sealingly engage the washpipe, or to allow coupling nuts to slide upon the washpipe assembly and engage the appropriate adjacent conduit. This may be accomplished by means of pressurized fluid as described, for example, in U.S. Patent Application Publication No. US2005/0242512, incorporated herein by reference. The pressurized fluid, such as air, may also be used to set or energize the seals. The use of pressurized fluid requires the worker to also carry or be provided a line for supplying the pressurized fluid. As will be understood, the complications associated with handling the washpipe assembly itself, in addition to pneumatic lines and a sledgehammer, make the operation awkward and time consuming to perform twenty or more feet above the drill floor. Further, given that drilling must cease during this replacement procedure and that drilling costs may be thousands of dollars per hour, it is desirable that the washpipe assembly be changed as quickly as possible, but with personnel safety a priority.
Accordingly, it would be an advance in the art if a more convenient and pre-energized or ready-to-install washpipe assembly was available so as to minimize certain safety concerns and speed up to the process of changing failed seals.